SNP LEADER Alex Salmond would give Scots a vote on independence in 2010 should he replace Labour's Jack McConnell as first minister.

The Banff and Buchan MP has today confirmed, for the first time, the timing of the referendum, its cost, and the exact wording of the question, following talks with the civil service.

His plans, which have so far been kept secret, are revealed in an exclusive interview with the Sunday Herald, in which he sketches out the details of his referendum plan.

Salmond, whom opinion polls claim is in line to be the next first minister, has made a referendum on independence the number one priority of an SNP-led Scottish Executive.

So far, he has insisted the poll on separation would be held "within the four-year term" of the Scottish parliament, but has never ventured beyond this timescale. However, he has now confirmed the independence vote will be at the end of an SNP-led term in office.

"I'm persuaded the key argument is about the SNP building up credibility in government, which is the essential requirement to win an independence referendum. The referendum would be close to the end of the four-year term," he says.

One factor, he says, is the next general election, which he believes must come before a Scottish referendum: "Would it be after the next general election? The answer is yes."

Still hedging his bets on the exact timing of the referendum, he says the poll would be staged in the "second half" of a four-year term. However, an SNP memo passed to the Sunday Herald clarifies Salmond's position: "SNP strategists have pencilled in the date 2010 for the referendum. The main argument being that this will give them time for the administration to prove itself in government and thus gain credibility."

Salmond also addressed the process by which he intends to deliver a referendum. A white paper, setting out the details of independence, would be laid within the first 100 days of the next parliament. An SNP-led Executive, he hopes, would then pass an enabling bill to give Scots the choice of independence in a referendum held in 2010.

However, in recent talks with the SNP, civil service officials expressed concern that the wording of the referendum question might not be covered by the powers of the parliament.

The civil servants instead suggested a new version which made clear the question had to be explicit about being based on the contents of the white paper.

Salmond said he could "not comment" on discussions with the Executive, but confirmed that a "tweaked" question had been drafted.

"Any talks with the civil service are private, but the wording on the ballot will be, The Scottish parliament should negotiate a new settlement with the British government, based on the proposals set out in the white paper, so that Scotland becomes a sovereign and independent state'. The responses would be Yes I agree' or No I disagree'."

In other words, a "Yes" vote would give Holyrood the right to negotiate an independence settlement, rather than a straight endorsement of a separate state.

As for the definition of independence in an SNP-led Executive's white paper, Salmond is keen to stress a separate state would involve ending the 1707 Treaty of Union, not the 1603 Union of the Crowns.

"That is the argument to transfer full political and economic control to Scotland, not to interfere with either the monarchy or social union between England and Scotland. The two countries will be independent but with the same head of state.

"After independence, the white paper will say, England will remain Scotland's closest friend, ally and trading partner."

Salmond believes separating political independence from republicanism will win his party support, although he declines to say whether his support for the current monarch means that he is a monarchist. He also downplays suggestions an independent Scotland would back an elected head of state.

"I cannot imagine the circumstances in which there would be a vote on the current monarch in her lifetime," he says.

The SNP leader's timetable for a referendum may be set in his own mind, but it is does not automatically follow that the parliament will give Scots a vote on independence.

SALMOND'S most likely coalition partners, the LibDems, are opposed to a referendum and say they will not budge on the issue. One senior LibDem told the Sunday Herald that the party might reverse their opposition if independence and more powers for Holyrood, the LibDem policy, were both on the ballot.

Could Salmond live with a multi-option referendum, rather than one simply on independence? "They the LibDems would have to say that to me under appropriate circumstances," he says, opening the door to such a possibility.

More broadly, the SNP leader admits his tactics for a referendum are modelled on Labour's delivery of a Scottish parliament. For instance, in 1994, Tony Blair said devolution could only come via a referendum, a strategy taken up by the SNP in 2001.

In 1997, the late Donald Dewar asked Scots to vote for a home rule package based on the contents of a white paper, an approach now adopted by Salmond.

The SNP leader says: "I would pay tribute to Donald Dewar. Having the referendum on the principle of devolution, in the style he did, was a act of near-genius. I learned about the referendum from him."

On the cost of an independence referendum, Salmond again points to the devolution precedent.

"The devolution referendum cost £5 million in 1997, so a comparable figure 10 years on would be in the region of £7m. FOI (freedom of information) figures that were reported a couple of years ago showed that the Executive was running a rate of 164 consultations a year, at an estimated cost of £5m per annum," he says.

His tactics, if they are not obvious already, are to break up Britain by copying an approach to constitutional change that was supposed to help save the union. So much for devolution killing nationalism "stone dead".